Deborah Cohan, MD, MPH is a full-time faculty member in the Department of Obstetrics, Gynecology and Reproductive Sciences at the University of California San Francisco (UCSF) and medical director of St. James Infirmary, a peer-based, multi-service clinic for male, female, and transgender sex workers. Dr. Cohan has just completed a two-year fellowship in Reproductive Infectious Disease and her Masters in Public Health. She proposes to build on her research skills by learning ethnographic techniques and advanced biostatistical methods, with the ultimate goal of becoming an independent clinical researcher. Dr. Cohan proposes to conduct a multi-level study to identify individual-level psychological factors and population-level network characteristics associated with risk of prevalent HIV-1, sexually transmitted infections (STIs), and hepatitis B (HBV) and C (HCV) among female sex workers in San Francisco. The study combines qualitative and quantitive methods, including ethnography, a cross-sectional survey using venue-based probability sampling, and social network analysis, to describe the sociopolitical, environmental, and psychological forces that underlie sexual and drug-using behavior among sex workers. She proposes three specific aims: (1) to characterize sexual and drug-using behavior and prevalence of HIV, STIs, HBV, and HCV, and to examine psychological risk factors associated with these infections among female sex workers in San Francisco; (2) to characterize social capital among networks of female sex workers in San Francisco; and (3) to investigate whether diminished social capital is associated with increased risk of prevalent HIV, STI and hepatitis among these networks. With these data, Dr. Cohan intends to develop and evaluate culturally-appropriate, community-driven prevention interventions for sex workers. Dr. Cohan has assembled a multidisciplinary team spanning the fields of epidemiology, psychology, and medical anthropology to ensure success of this project.